Wilkinson, Michael

THE DEPARTMENT OF ENERGY ORAL HISTORY
PRESENTATION PROGRAM
OAK RIDGE, TENNESSEE
AN INTERVIEW WITH MICHAEL K. WILKINSON,
FREDERICK W. YOUNG, AND
RALPH M. MOON
FOR THE
OAK RIDGE NATIONAL LABORATORY
ORAL HISTORY PROJECT
INTERVIEWED BY
STEPHEN H. STOW
AND
MARILYN Z. MCLAUGHLIN (ASSISTANT)
OAK RIDGE, TENNESSEE
APRIL 30, 2003
TRANSCRIPT BY
BRIAN VARNER
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STOW: Today, we’re going to be talking to three individuals -- Mike Wilkinson, Fred Young,
and Ralph Moon. They have all been very much involved with neutron scattering and materials
analysis work here at the Laboratory, starting as early in some cases, as 1950. So, we look
forward to a good talk with them and learning more about the history of neutron scattering in the
Solid State Division, High Temperature Materials Laboratory (HTML), Advanced Neutron
Source (ANS – never built), Spallation Neutron Source (SNS), and other important parts of Oak
Ridge National Laboratory and its history.
We’ve started off our interviews typically by asking how and why you got interested in science or
technology. Fred, give us a quick review of what got you into this area to begin with years ago.
YOUNG: It’s not an easy answer -- not a short one. I went to graduate school and only there did I
begin to realize what science was all about. And, I had a really interesting professor, who had a
big influence on my becoming a scientist and deciding to try to compete worldwide in research as
opposed to taking a teaching job at a small school or a job in industry, which were common
things to do at that time. And, it just happened at about that time that Oak Ridge National
Laboratory became open to the public. Oak Ridge Associated Universities, or ORAU, started a
program of having college and graduate students and faculty members come for the summer. I
asked ORAU if it would be possible for me to come to ORNL for a year. This was about the time
I graduated. And, they thought about it a little bit and decided it would be a good thing, so I did
that.
STOW: That was about 1950, right?
YOUNG: Yes, 1950.
STOW: Okay.
YOUNG: I spent a year here and then went back to the University of Virginia, which was part of
the agreement. I finally came back to the Lab in 1956 and stayed here until I retired.
STOW: Did you have any idea at that time that you'd spend your entire career here?
YOUNG: No, not really. But I had more connection with it than most people when they came
because I spent a year here and then I was a consultant in between. So, I was here frequently and I
pretty much knew what I was getting into when I came back. So I thought I would stay here a
long time, anyway.
STOW: Mike, what got you into science originally?
WILKINSON: Well, I guess I really got interested in science in high school ... taking courses in
chemistry and physics and mathematics. And, I really liked them very much. When I went off to
college, I actually thought I was going to be a chemist. But a very good professor I had in my
first-year physics course -- he was department chairman -- influenced me to change my mind and
become a physicist. After I graduated from the Citadel, I immediately went into the Army, which
sent me to radar school at Harvard and MIT. I spent most of my time in the Army as a radar
officer. At the end of the war, I decided to go back to MIT and pick up where I had left off in
radar school. I guess the professors I had there made me very interested in research. Prior to that,
I think I’d wanted to be a teacher. But, I decided I wanted to get some research experience first.
also wanted to come farther south. About the only place you could do research at that time and
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come farther south, without being associated with a university, was Oak Ridge. And, my
background at that time fit in pretty well with ORNL’s Neutron Scattering Program.
STOW: Yes.
WILKINSON: At that time, there was no such thing as “training” in neutron scattering. I mean,
it was brand new and you just had to have a background that was somewhat similar, and I had
that. I came here and went to work with Ernie Wollan and Cliff Shull.
STOW: Yeah, we’re going to talk about them in just a minute. Now, Ralph, you’re the new kid
on the block here.
MOON: That’s right.
STOW: What got you interested in science?
MOON: Well, I think it started in high school. Math and science were my favorite subjects. My
father was an engineer, as was my older brother. I just assumed that I would be an engineer so I
enrolled in the engineering school of the University of Kansas. And, it was during my freshman
year as an engineer that I discovered (laughs) I really didn't want to be an engineer.
STOW: Yes.
MOON: I much preferred a little more freedom to do basic science, so I switched to pursuing a
bachelor of arts degree in physics. And, I haven't regretted it. Eventually, I ended up at MIT in
graduate school just when Cliff Shull, who had left Oak Ridge to go to MIT, was getting his
experimental program started at MIT. So, I was his first Ph.D. student. And, it was sort of natural
for me to come to Oak Ridge.
STOW: And, that was in ’63, I think.
MOON: That was in ’63. And, I just continued what I started under Cliff Shull at MIT.
STOW: Is it safe to say that neutron scattering really had its birth here at Oak Ridge -- with the
Graphite Reactor?
MOON: Oh, it did. No question about it.
WILKINSON: Oh, absolutely.
STOW: With Ernie Wollan and Cliff Shull.
WILKINSON: Yes, that's right.
STOW: In retrospect, what was the importance of the work that Wollan started before Shull
came?
WILKINSON: Actually, Cliff won the 1994 Nobel Prize in Physics for the [pioneering neutron
scattering research at the Graphite Reactor], but there's no doubt that it was a two-person
program. Many times Cliff stated that it was just too bad this award wasn't made many years
earlier when Wollan was still alive, so he could have been a co-recipient. But, Wollan did start
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the program at the Graphite Reactor in November of 1945. He actually had sent here a
spectrometer that had an X-ray spectrometer that he used at the University of Chicago. He
installed it at the Graphite Reactor. Incidentally, this spectrometer is now on exhibit at the
American Museum of Science and Energy in Oak Ridge. But, at that particular time, the main
interest was in measuring the scattering power of atoms by neutrons. And, I won't go through all
of the details of what they went through, but the point is -- unlike X-ray scattering where you can
calculate the scattering power -- you can't calculate it for neutrons. You have to measure
everything experimentally.
STOW: Yes.
WILKINSON: And, before you could measure the first one -- you had to put the technique on an
absolute basis -- a quantitative basis. They went through many trials and tribulations. One of their
first successes was the use of powders, instead of single crystals, to scatter the neutrons. This
switch eliminated the problem of extinction that you have with large single crystals. I won't go
into that detail either, but it's a rather complicated effect that involves scattering within a large
crystal such that the scattered intensity [of the neutrons] is quite different from what you should
be getting. I think their use of polycrystalline materials was really the key to the success of their
whole program. After that, they had to untangle a lot of things, such as the isotopic effects of
scattering and the spin incoherent effects of scattering from a nucleus. They had a lot of problems
with multiple scattering. But, in any event, they were able to put this technique on a firm
foundation and use it for some very important experiments in nuclear physics, crystallography,
and magnetism. The crystallography work was primarily associated with hydrogen atom
crystallography. You cannot locate hydrogen atoms by X-rays because the X-ray scattering power
of hydrogen is very small. So, [hydrogen atom crystallography using neutrons] turned out to be
an entirely new field in itself. And, Henri Levy started a program within the Chemistry Division
here based strictly on hydrogen atom crystallography to measure the positions of hydrogen atoms
in crystals and study hydrogen bonding. Cliff and Ernie focused on magnetism, which is the other
very important field. But, the really important thing is that they did all this work here first. If they
had not established the foundation for [neutron scattering research using a reactor], it would not
have grown up around the world as it has.
STOW: For the laymen out there -- put in simple ... terms -- what's the practical importance of
neutron scattering? What does it tell us? I mean, what is the purpose of it?
WILKINSON: Well, the purpose of neutron scattering is that it is one of the best techniques
available for studying the properties of materials and characterizing materials. If you want new
materials in any technology you need, you've got to actually be able to study and characterize the
new materials properly. Neutron scattering is one of the best techniques you can use. It has made
a tremendous impact not only in physics and chemistry, but also in biology and various types of
engineering polymers and medical problems. It's just a tremendous technique.
STOW: And, Ralph ...
MOON: One interesting bit of history that Mike skipped over is that the first instrument Ernie
Wollan brought from the University of Chicago was actually designed by Arthur Compton, who
was a Nobel Prize winner and Ernie's thesis advisor. This instrument was used by Compton and
Wollan in Chicago and then Wollan brought it here. Some twenty or twenty-five years later, it
was in use again on another piece of Nobel Prize-winning research.
STOW: My goodness.
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MOON: So, it's really a unique piece of apparatus. And, it still exists at the American Museum of
Science and Energy here in Oak Ridge.
STOW: I'll be darned. I didn't realize that. I ought to go over there and take a look at it.
MOON: Well, it's hard to find.
STOW: Is it?
MOON: I mean, it has been on conspicuous display occasionally, but not routinely.
STOW: Well, now, Fred, you were more into materials analysis, weren’t you? Tell us a little bit
about the work that you’ve done in materials analysis and radiation effects, and so on.
YOUNG: Yes. Well, the Solid State Division was actually formed to study radiation effects in
solids. Neutron scattering was not a part of the Solid State Division in the beginning. The Solid
State Division was formed in various steps in the late '40s. And, about 1951, it actually became a
division. In the beginning, there was no study of this sort going on at Oak Ridge National
Laboratory at all. But, it was realized early on that energetic particles striking solids would cause
disorder in the lattice of these solids. Most of the materials we have been interested in are
crystalline materials. A crystal is defined as an ordered arrangement of atoms.
STOW: Sure.
YOUNG: And, where the arrangement is disordered, a defect exists. If an atom is out of place,
that's a defect. Or, it could be a group of atoms out of place. There are various kinds of defects.
This was a subject itself that was just in its infancy at the same time that the study of radiation
effects was in its infancy. So, the two were used in complementary ways and "grew up together,"
so to speak. I was fortunate enough to be at the right place at the right time and participate in that.
And, so we investigated here in the division, all sorts of materials. It was important practically to
know what happened. We had to build reactors, and the materials the reactors were built of were
exposed to fast energetic particles, such as neutrons, alpha particles, protons, electrons, and
gamma rays.
STOW: Sure.
YOUNG: First, we had to put [target materials] into the Graphite Reactor and see what happened
to them. And, we had to develop methods of measurement to make quantitative statements about
a material. There was some theory, but not much. All of this developed sort of simultaneously,
and we were part of it. We looked at metals, semiconductors, ionic crystals, polymers, and
elemental materials like graphite, for example. It turned out that Doug Billington was one of the
early people here in [research on materials]. He actually came to the Oak Ridge School of
Reactor Technology first after the war was over. And, then he became head of the Solid State
Division. He did some of the first experiments and saw clearly that [studies of radiation effects on
materials] should be expanded. He led that program for twenty-five years approximately.
STOW: Of course, all three of you fellows had been the head of the Solid State Division either in
acting capacity or a longer-term capacity. Solid State Division is an interesting name.
MOON: Well, you know, it's been changed ...
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STOW: It's been changed around, I know. [It became part of the Materials Science and
Technology Division at ORNL.]
YOUNG: The term solid-state physics became the name of a division of the American Physical
Society, in 1949, if I'm not mistaken.
STOW: Okay.
YOUNG: I think that's correct. And, it was called solid-state physics. But, there's also a field
called solid-state chemistry.
STOW: All right.
YOUNG: And then, there were the terms metallurgy, ceramics, and polymer science. All of these
fields dealt with solids. We had a group of people investigating various solids who were trained
in chemistry, physics, or ceramics sciences.
STOW: Yes.
YOUNG: And so, rather than call it any one of them, they started just calling it "Solid State."
That was a discussion that went on at the time that the division was first named.
WILKINSON: I think a better name probably would have been the Solid State Sciences
Division.
YOUNG: Yes, I think it would have. But, the managers did not name it that.
STOW: Well, I've always been curious about where the name came from. I mean, it could have
been the Liquid State or Gaseous State Division. (laughter) As I was reading about the
background of the division and some of your backgrounds, I learned there was a Research
Materials Information Center established in the 1960s in the division. Who can tell me something
about that?
WILKINSON: Well, I'm sure that Fred or I, or Ralph could, but let me just start.
STOW: Okay.
WILKINSON: As Fred said, most of the very early work in the division involved studying the
production of defects [in crystalline materials] and annealing these defects by raising the
temperature of the sample. Well, if you start off with a sample that already has a large number of
defects in it, then you actually end up "masking" the whole situation that you're studying.
STOW: All right.
WILKINSON: So it was pretty apparent at the time that very nice, perfect crystals that were
defect free and of high purity were needed in these research investigations. The Materials Science
Division of the Atomic Energy Commission at that time decided it would be nice to start a
program that would actually concentrate on developing techniques for producing very-highquality
materials and using the materials, not only in Oak Ridge, but also at other laboratories
sponsored by the Atomic Energy Commission.
YOUNG: And also worldwide.
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WILKINSON: At roughly the same time, an information center was set up for keeping track of
where these materials were being prepared, who was preparing them, what their characteristics
were, how to go about getting them. And, an up-to-date list was published periodically and sent
both to the research users of the materials, and to the producers. The users needed to know where
they could get the materials, and sending the list to the producers kept them from duplicating
what was already being done someplace else. It turned out to be a small program. But, at the time,
we didn't have information centers all over the place like we have now. We didn't have a lot of
people concentrating on growing large single crystal specimens, so it was a very important
program.
STOW: What ever happened to that information center?
YOUNG: It lived its life.
WILKINSON: That's right. The other information centers in material sciences were developing
throughout the country under the sponsorship of other agencies. There was a big overlap in the
programs. The ORNL center was run by a research program, not by a DOE administrative
program. The Lab decided it was better to spend the money for research because the information
center duplicated the efforts of other organizations.
STOW: Okay. Let me ask about one other historical aspect. Fred, maybe you can reflect on this
best. In 1962, some pioneering work was done on ion channeling. Can you explain the
importance of that?
YOUNG: Yes. In general, atoms are aligned in the lattices of crystals. If you make a model of
this lattice, you can look through it in one direction. You can see many more holes all the way
through than if you look in a random direction.
STOW: Yes.
YOUNG: So, if you look in specific directions in a model of a crystal, your natural reaction is
that holes are in there. But, these models are not realistic either; in fact, the electrons orbiting
around the nuclei in all positions overlap and join in these open areas. So, we had begun to think
that in a cubic lattice [the movement of atoms through a crystal] was isotropic. For instance,
atoms diffusing through the crystal would diffuse in all directions with equal ease, with equal
velocity. We had convinced ourselves in a way that holes did not really exist throughout the
lattice. But then, in order to explain some scattering results, Mark Robinson became involved in
an experimental program. He started doing some calculations in a time when general use of
computers was just beginning. He was rather clever at using computing in ways that were
somewhat more advanced than what other people had been able to do. He found experimentally
and theoretically that when atoms were sent down in a certain direction in a crystal, they
penetrated a lot farther in that direction than in other directions. What’s more, the atoms moving
in that direction were not just the ones sent directly along the lattice, but also the ones that
bounced off atoms in the crystal in a way that let them go through it farther. This phenomenon,
discovered at ORNL, is called channeling.
STOW: All right.
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YOUNG: They decided to name it ion channeling because the lattice "channeled" charged atoms,
enabling the projectiles to go through the crystal. And so, at first, we wondered whether this was
true or not, you understand. And then, lo and behold, some people at Chalk River Laboratory in
Canada who were investigating ion implantation discovered the same effect, which was found to
be channeling. And then, the whole world woke up to the new phenomenon, and immediately it
began to be a very important subject. Robinson continued his research with Ordean Oen, and
Mark and Dean together performed the calculations. They broadened their program and then we
began to develop programs here. And, at the present time, ion implantation is used to adjust the
concentration of charged carriers in semiconductors.
STOW: Yes.
YOUNG: And, this understanding of channeling is the basis of that whole industry now.
Channeling effects must be taken into account properly. You can't do ion implantation exactly
along the axis of a silicon crystal. You've got to cock it off just a little bit.
STOW: Yes.
YOUNG: And then, you can determine exactly how far all the atoms will be implanted into it.
And, I mean, this was a tremendous achievement. We're in the silicon age, aren't we? This is of
tremendous importance to the whole industry. It turned out also that some really nice theoretical
and experimental studies were done here, showing you could use this as a way of determining
interatomic potentials.
STOW: Okay. So, a lot of that fundamental work that we're benefiting from today in silicon
technology came out of the Solid State Division in those years.
YOUNG: That's quite true.
STOW: Neutron scattering -- the Neutron Scattering Program -- has really been one of the
longest continuing programs at ORNL stretching back to 1945. How has the program changed as
new reactors have come online? We started with the Graphite Reactor, and, of course, have been
through thirteen, fourteen, fifteen different reactors here at the Laboratory over the years. How
have changes in reactor technology influenced the neutron scattering program and its ability to
achieve new objectives? Ralph, would you want to jump in on that?
MOON: Yes, sure. Three reactors have played key roles in the Neutron Scattering Program. The
first was the Graphite Reactor, where the flux of neutrons is measured in neutrons per square
centimeter per second. That number tells you how many neutrons are flowing into your
experiment. At the Graphite Reactor, that number was around 1012 neutrons per square centimeter
per second. We then went to the ORR, the Oak Ridge Research Reactor, where flux number
increased enormously to 3 times 1014 -- a factor of 300 larger than the flux at the Graphite
Reactor. Finally, we did neutron scattering research at the High Flux Isotope Reactor, where the
neutron flux was boosted to 1015. What happened is that the complexity of the experiments
followed that increase in flux. When you get more flux, you usually don't just do experiments
faster. You do experiments that you couldn't do before because you didn't have enough neutrons.
So, at the Graphite Reactor, elastic coherent scattering was the main technique used because the
researchers could measure the number of neutrons scattered through a particular angle. Beginning
at the ORR, another type of experiment involving inelastic scattering, in which both the number
of neutrons scattered through a particular angle and their change in energy could be measured.
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So, neutron cross sections were measured as a function of energy and momentum. When we got
to the High Flux Isotope Reactor, we created a new sort of experiment, in which we not only
measured the scattering angle and energy change, but also the spin of the neutrons in a beam. In a
magnetic field, the spin of one half of the neutrons can be either up or down. We'd known for a
long time how to produce polarized beams of neutrons, so we could produce a beam where the
spins of all the neutrons are up. We also had the technology for flipping those spins from up to
down. So, what we did at the HFIR was -- in addition to measuring energy and momentum
changes – was to measure how many neutrons in a beam came on the sample up-spin and how
many came off the sample up-spin.
STOW: Okay.
MOON: A different problem was to determine how many neutrons came on the sample with
down-spin and how many came off the sample with a down-spin. Also, we tried to determine the
probability that some neutrons would flip their spin – come into the sample up-spin and come off
the sample down-spin. Theory told us that for certain types of systems, all those cross sections
(probabilities) would be different. We found new information in each "spin dependent" cross
section. We experienced a gradual evolution as experiments became more and more complex as
the source flux got bigger.
STOW: So, we've had three reactors that have influenced the program -- the Graphite Reactor,
the Oak Ridge Research Reactor, and the HFIR.
MOON: That's right.
STOW: But, Mike, there are sources of neutrons that are not from reactors, right?
WILKINSON: That's right.
STOW: Has the Neutron Scattering Program here relied solely on neutrons from nuclear
reactors?
WILKINSON: Well, are you thinking in terms of accelerator-type neutrons?
STOW: Yes, I think so.
WILKINSON: Well, there's been very little neutron scattering here done using accelerators.
Herb Mook has done some experiments at our accelerator facilities, but, of course, a lot of it is
going to be done fairly soon on an accelerator when the Spallation Neutron Source is finished.
STOW: That's right.
WILKINSON: The types of experiments you do at research reactors and accelerator-based
neutron sources, such as the SNS, are a little bit different, but, nevertheless, equally as important
and equally meaningful, with respect to the information you get. In the pre-reactor days, scientists
observed neutron scattering using very small sources, such as radium-beryllium sources, but they
didn’t learn anything, because there were not high enough intensities to do any meaningful
experiments.
STOW: Fred, you were involved in the 1970s with the planning and the establishment of the
High Temperature Materials Laboratory. Tell us a little bit about your involvement there.
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YOUNG: My involvement really started at the time when the Atomic Energy Commission
became the Energy Research and Development Administration and then the Department of
Energy. At that time, we were constrained to study materials of interest to the nuclear programs.
We weren't funded to look at anything we wanted to.
STOW: Yes.
YOUNG: With the onset of the Department of Energy in 1977, we were asked to investigate
materials problems related to all energy technologies. So, this opened up a tremendous new area
for us. It became apparent immediately that for many of the energy technologies, including
nuclear, high-temperature materials were very important [because fuel is used more efficiently
when machines are operated at higher temperatures, but research is needed to identify or create
structural materials for such machines that can endure high temperatures for a long time]. We had
no programs in that area to amount to anything in the whole country in the atomic energy
laboratories. So, the origin of the HTML here began when Don Stevens, head of this program,
asked me to meet him in Washington. Then he asked me to go to several other laboratories
around the country and determine what was going on in the area of high-temperature materials,
and what we should be doing about that. Well, after a long process, I came back and wrote a
report in which I stated that some really exciting [research on high-temperature materials] could
be done here. I said that it was appropriate for the Department of Energy to sponsor a program of
this sort. Well, it took many years to realize [this vision], but ultimately, the High Temperature
Materials Laboratory [was designed and built at ORNL]. And, I was involved with it over that
whole period of time. It was finally decided to put HTML into the Metals and Ceramics Division,
as opposed to the Solid State Division. That was a somewhat arbitrary decision but not an
unreasonable one. And, I was proud of my efforts in that respect. I think I had a lot to do with it.
STOW: Well, that's something to be proud of, because the HTML is one of the cornerstones of
our materials science work here in Oak Ridge.
YOUNG: Yes, yes. It was created out of whole cloth in a way, because there was almost no
[study of high-temperatures materials] here. And, almost none in the whole set of DOE
laboratories.
STOW: Well, Fred, you've touched on a couple of things that I want to ask you about, Mike. You
were division director for Solid State Division starting in 1972, I believe, and up into the 1980s.
So, you were division director during the transition from the Atomic Energy Commission to
ERDA to DOE. As manager of the division, did you experience problems with that transition?
WILKINSON: Well, we didn’t experience any problems. It sort of opened the door for us. The
point is that the research done in the Solid State Division is mission-oriented research. That
means that you do research on materials and their properties that are important to the mission of
your sponsor. There's one exception to that I might point out, and that's the Neutron Scattering
Program. The exception is that, it's acceptable to use the major facilities that have been built by
the sponsor here at the Laboratory to study materials of any kind that can't be studied by other
techniques.
STOW: All right.
WILKINSON: For the Lab’s Neutron Scattering Program in the Solid State Division, the
determination of which types of materials to study was not as restrictive as was the case in other
parts of the division. But, under the Atomic Energy Commission, of course, we were restricted to
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work on materials associated with fission and fusion reactors. Under ERDA and then the
Department of Energy, materials associated with all energy technologies were of interest. ERDA
and DOE’s mission [embraced] not only fission and fusion energy, but also fossil energy,
geothermal energy, magnetohydrodynamic energy, energy storage, energy conservation, and so
forth. Well, all of these [energy technologies] were materials limited. Advances in energy
technologies [to increase supply and reduce demand] required new materials. So, it was very
interesting from my viewpoint to be [encouraged] to expand our program from a fairly restricted
one involving mostly materials radiation and neutron scattering, to almost anything else we
wanted to do. And, we got some extra money for starting new programs, but a lot of it was
associated with redirecting some of the programs in radiation effects to other areas. As a matter of
fact, nowadays relatively little research is going on in the radiation effects studies; most of this
type research is tied into other efforts in a very broad program. It was a tremendous opportunity
for us to be able to expand our investigations. The Solid State Division has developed into one of
the broadest materials programs in the world, and certainly one of the best. It's one of the best
organizations in the world for studying different types of problems in the materials sciences.
[Since 2009 SSD and the Metals & Ceramics Division became parts of the newly named
Materials Science and Technology Division at ORNL.]
STOW: Well, in 1971, I think, Alvin Weinberg, Laboratory director, asked you and Sheldon
Datz to look into opportunities in nonnuclear research and the basic physical sciences. Is what
you've just described an outcome of some of Alvin's foresight?
WILKINSON: Alvin jumped the gun here in that he established committees for looking into
[areas of nonnuclear energy research]. We did actually publish a report on it, which the
Department of Energy found very useful, once they got involved in all other types of energy. As a
matter of fact, the so-called nonnuclear energy technologies and the materials associated with
them turned out to be key to their programs.
MOON: You mentioned Alvin’s forward-looking thinking. Let me mention one example of that.
STOW: Okay.
MOON: From the beginning, he had recognized that neutron scattering was very important
scientifically, but he played a really crucial role when the HFIR was being built. The HFIR was
designed to produce transuranic isotopes but the original design had no provision for neutron
scattering.
WILKINSON: No beam holes ...
MOON: No beam holes. Alvin Weinberg insisted that they could not build this reactor without
putting in beam holes [for neutron beams] so that neutron scattering could be done at the reactor.
STOW: And, they put in four beam holes, I think.
MOON: Four beam holes, yes.
STOW: So, that really was a key part of the Neutron Scattering Program.
MOON: Absolutely, yes.
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WILKINSON: Well, the engineers were afraid, because of the type of reactor it is. They said
they were afraid that putting in the beam holes would affect the operation of the reactor. That's
the reason they compromised on just four beam holes. It's too bad they didn't put in a lot more.
But, as it turned out, of course, the beam holes did not affect the operation of the reactor and have
really been a tremendous help to the Neutron Scattering Program here at the Laboratory.
STOW: Fred, you took over as division director in 1988, I believe. What were your feelings and
thoughts at that point in your career in taking over an administrative role like that?
YOUNG: Well, unfortunately, my time as division director was simultaneous with [the visits of
and issues raised by] the so-called Tiger Teams. [They were sent to ORNL by DOE to check on
compliance with environmental, safety, and health regulations].
STOW: Okay.
YOUNG: (laughs) So, a lot of my efforts had to go toward dealing with those issues. I didn’t
enjoy that very much. Doing research is much more fun than being an administrator. But, I think
Mike told me this one time: it didn't make so much difference about how many more research
papers I published, as it did whether the Solid State Division developed into a powerful
institution as it did.
WILKINSON: Well, let me interrupt him for a minute.
STOW: Okay.
WILKINSON: He didn't just become a division director and become involved in the
management of the division. Fred had been an associate director for a long time ...
STOW: Sure.
WILKINSON: ... and as associate director, he had also been highly involved in division
management.
YOUNG: You know, I was quite familiar with management, and so it wasn't an exceptional
chore ...
STOW: I understand.
YOUNG: ... except for this Tiger Team business. That was pretty late in my life here.
Unfortunately, it was a time of change in the Department of Energy and its way of funding things.
Funds were taken away from research programs to help solve the cleanup problems that we had
from earlier handling of radioactive materials here at Oak Ridge.
STOW: Yes.
YOUNG: And, I felt that was unfair. We had not been the ones that had caused the problem, but
we had to pay for it. And, we did get a chunk of that. But, nevertheless, it was also an exciting
time because we were doing a lot of new and interesting research then. I was proud to be part of
it. I did want to make an addition to what was said earlier by Mike and myself on the studies of
irradiation effects.
13
STOW: Okay.
YOUNG: By the end of the 1970s and early ‘80s, we had, to a large extent, both theoretically and
experimentally, categorized the irradiation effects. And, they were reasonably well understood
then.
STOW: Yes.
YOUNG: And, so it was natural that we use this expertise to investigate other types of problems.
We went from being certainly one of the best-- if not the best -- radiation effects laboratories in
the world -- to one of the best general solid-state physics laboratories in the world, over a few
years, from the onset of DOE to the time I left. We opened up a lot of new areas of research that
utilizes the facilities and people that we had. And, that's what research management is about, and
that part is okay. It's just those Tiger Teams ... (laughter)
STOW: I get the impression you didn't care for the Tiger Teams that much. I don't think anybody
did, frankly. (laughter) Ralph, you served as an acting director of the division for a period of
time, but I want to ask you more specifically how you got involved with the ANS. Tell us a little
bit about your involvement there and what happened to ANS in the long run.
MOON: Well, there's a lot of prehistory to the ANS, which is also prehistory to the SNS ...
STOW: Yes.
MOON: It started when both the High Flux Isotope Reactor here, and the High Flux Beam
Reactor at Brookhaven National Laboratory, were built and came online in the mid-1960s.
Shortly after that, the neutron community, not only the scattering community, but other scientists
that used reactors, got worried that DOE -- or I should say at that time, the AEC – was not
thinking ahead about the next-generation neutron source.
STOW: Yes.
MOON: There was a workshop in '73 called “The Workshop for Intense Neutron Sources,” held
at Brookhaven. From this Lab, Mike, Alvin Weinberg, and Wally Koehler went to it. Their
recommendation was that the AEC should really start thinking about the next-generation neutron
source. At that time, Argonne National Laboratory had already started thinking about “pulsed
sources,” or spallation sources of neutrons.
STOW: Okay.
MOON: ... so that was in 1973. And in ‘77, a National Research Council group did a study of
neutron sources, with Cliff Shull as the chairman. The group recommended that people in charge
should start thinking about new neutron sources. In 1980, a DOE panel headed by Bill Brinkman
made the same recommendation: start thinking about new neutron sources. In '83, there was a
local competition. Alex Zucker and Herman Postma had decided that it was time for the
Laboratory to go after a big new facility and that it was going to be a neutron source.
STOW: Okay.
MOON: So, the next decision to be made was whether to go for a reactor or for an acceleratorbased
spallation source. And, I was the guy in charge of making arguments for the reactor. Dave
14
Olsen was in charge of making arguments for the spallation source. So, we had a big management
meeting in which we both presented cases, and the Laboratory decided to go for a new reactor.
Well, the decision was made at that time to upgrade the HFIR. Postma and Zucker didn't want to
go for a new reactor. They wanted to upgrade the HFIR. We got money starting in '84 from the
internal Laboratory Directed Research and Development (LDRD) Program to begin a small
project about planning upgrades to the HFIR. The same day we got that money, we received an
invitation to appear before another National Research Council meeting in March. It was January
1984 that we got the money, and we had to appear in March before the National Research
Council group, whose mission was to decide which major facilities DOE would fund. This was
the Seitz-Eastman committee. They decided that DOE’s first priority should be to build an X-ray
synchrotron source, which became the Advanced Photon Source, the APS [which was built at
Argonne National Laboratory]. The Advanced Neutron Source (ANS) reactor was the second
choice. Argonne representatives were there touting an [accelerator-based] spallation source,
which was the fourth choice. At that point, the decision was made to go for a new reactor. This
committee didn't want an upgraded HFIR. They wanted a brand new facility. So, the ANS took
off from that point. When it came to funding the ANS, the federal government found it was a lot
more expensive than people thought, and the timing was wrong. Our country was having these
massive deficits every year. So the decision was made to not fund the construction of the ANS,
but the scientific case for a new neutron source had been made.
STOW: Yes.
MOON: And, the decision had been made to put a neutron source in Oak Ridge. So, the decision
to try for a spallation source was natural, and the timing was right. When the conceptual design
report was completed and DOE wanted to ask for construction money, we had this magic moment
when there was a surplus in the federal budget. And, that was very important, I think, in getting
funding for the spallation source. But, the whole prehistory -- the scientific case for a new neutron
source was made beginning in 1973 and going up to now -- and when the arguments came about
whether a spallation neutron source should be built in Oak Ridge -- the scientific case had already
been made.
STOW: That's an interesting history. I didn't realize all that. And, we'll be talking to Al
Trivelpiece about his role in the SNS. So, I appreciate the background there. Mike, let me ask you
one quick question here.
WILKINSON: Could I insert something? I've just been sitting here thinking about our
conversations involving, particularly, the neutron scattering and materials research, and in all of
this, Wally Koehler's name has not been mentioned.
MOON: I was going to mention him ...
WILKINSON: I wanted to make sure that we recognize that Shull and Wollan started the
program, and Wally Koehler joined their group in 1949 ...
STOW: Yes.
WILKINSON: ... I became the fourth member in 1950, and Wally stayed here and performed
some beautiful neutron-scattering research for many years. As a matter of fact, he led the classic
work done here on interpreting the magnetic scattering from rare-earth metals and alloys, and
both he and the Laboratory got a lot of credit for it. I just want to make sure that this oral history
mentions his name.
15
STOW: Good. I'm glad you did. And, let me follow up on that. I'm going to ask all three of you
the same question. In your career here at ORNL, has there been any particular individual who has
influenced you in a positive fashion, been your mentor, or influenced the direction in which your
research has gone? Mike, do you want to answer that?
WILKINSON: Well, there’s no question in my mind that Cliff Shull was a very strong influence
on what I did here. When Ralph said he was Cliff’s first graduate student, I wanted to say, “Well,
I was Cliff’s first postdoctoral student.” I really didn’t come here in a postdoctoral position, but a
postdoc is what I was. I worked with him very closely for five years and learned a tremendous
amount from him. So, there’s no question that as far as my research was concerned, he was the
main influence.
STOW: Ralph, what about you?
MOON: Yeah. Well, certainly Cliff influenced me when I was a graduate student, but when I
came here, I started working closely with Wally Koehler ...
STOW: Yes.
MOON: And, we collaborated closely for probably, sixteen, seventeen years after I came here in
'63. I certainly learned a lot from Wally and benefited from his experience and his choice of
scientific experiments to go after.
STOW: Fred, do you have any insights on this?
YOUNG: Well, I didn't have the same type of experience. There was not a world-famous
scientist in my area that I learned from. I was on my own more from the very beginning. But, one
thing that helped the Solid State Division, in my view, was the interaction we had with other
laboratories and universities in this country and around the world. And, in particular, I would like
to mention a theorist in solid-state physics named Gunter Liebfried, a German located at the
University of Aachen. He had learned his solid-state physics as the field grew up in Germany
prior to World War II when it was put on a firm theoretical quantum-mechanical basis.
STOW: Yes.
YOUNG: He spent one year here and then, after that, a couple times [during each of the next few
years] he would come to ORNL and stay six weeks and work with theorists primarily. But he also
worked with me a lot.
STOW: Okay.
YOUNG: And, I learned an awful lot from him. I got just a basic sort of understanding of solidstate
physics, because I was not trained in that area at all, you understand. And, he had a big
influence on me. Other than that, everybody influenced me. I was getting all the help I could at all
times, but I didn't have a mentor in that sense.
STOW: All right. Fred, look back on your career and tell me if you have one research
accomplishment that you’re most proud of. I want to ask all three of you to quickly reflect on
that.
YOUNG: I developed techniques for looking at defects in metals that scientists have used since.
16
STOW: Good.
YOUNG: I think that was the way I became recognized scientifically in this country and around
the world. I was able to prepare samples of copper and then do experiments with them to show
that I knew what I was talking about. This was new entirely for metals, in particular, at that time.
And, I gained some national and international recognition for this work.
STOW: Mike, what would you be most proud of as a contribution to science?
WILKINSON: Well, actually, as far as research is concerned, the work that I did with Cliff Shull
was, I think, extremely important. But, I continued studies of magnetic materials after he left, and
I think I did some very important work there. But, I would like to think that I would be
remembered as much as anything else for the developments that took place in the Solid State
Division. Fred and I worked very hard on this and it became one of the best organizations in the
world for doing research in materials sciences.
STOW: Good.
WILKINSON: I think that both of us would like to be remembered as much as anything else for
our contributions in making it happen.
STOW: Well, we'll make sure you are. (laughter)
YOUNG: I think that we both realized at sometime relatively early on that that was a role that we
were best suited for, given the circumstances here and the people here. We gave up our treasured
experiences as experimental scientists in order to help everybody else do a better job.
STOW: Well, it takes all sorts of people to make this place operate. And we’ve interviewed some
people who acknowledge that. They have said something like “Hey, I was not a good scientist
necessarily, but I was a better administrator.” And Ralph, what would you say your greatest
contribution has been?
MOON: Well, it was one of the early experiments at the HFIR, where we developed the
polarization analysis technique. It came about in almost an accidental way. A fellow named
Tormod Riste, who was an outstanding scientist from Norway, came to Oak Ridge. I was going to
work with him on doing some other experiment at the HFIR, one of the first experiments to be
done out there. We actually started that experiment when the HFIR went down because of a
problem, and [the shutdown] lasted six weeks. Tormod was sharing an office with me, so we
often talked about neutron scattering and the theory of neutron scattering. It came to us that we
already had the equipment to do some very interesting experiments related to measuring whether
the neutron had flipped its spin [from up to down, or vice versa] or not when it scattered from a
sample. So, we just forgot our plans to do this original experiment and started thinking about
polarization analysis experiments. When Wally Koehler heard our conversations, he wanted to
become a part of that. So, that was it. The three of us did this kind of experiment. Everyday, it
was a different thing. We were trying something brand new that nobody had ever done before.
And, we had lots of opportunities for brand new experiments. It was just really great fun.
STOW: Good. Where would you guys say the center for neutron scattering is now worldwide? Is
it in Europe?
17
MOON: Yes. Probably at the reactor at the Institut Laue-Langevin in Grenoble, France.
WILKINSON: That has been for many years probably the world’s single largest center for
neutron-scattering research. The ILL reactor was built strictly for doing neutron scattering
research. It is a high-flux reactor with many beam holes. I think that the world’s center for
neutron scattering research is going to be taken away from ILL when the Spallation Neutron
Source (SNS) is operating and the modifications of HFIR are made.
STOW: Well, that's a good way to leave the interview then -- looking toward the future when
Oak Ridge will return as the world’s center of neutron scattering. Thanks very much, fellows.
MOON: Thank you.
WILKINSON: Thank you.
-----------------------------------------------END OF INTERVIEW-----------------------------------------

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THE DEPARTMENT OF ENERGY ORAL HISTORY
PRESENTATION PROGRAM
OAK RIDGE, TENNESSEE
AN INTERVIEW WITH MICHAEL K. WILKINSON,
FREDERICK W. YOUNG, AND
RALPH M. MOON
FOR THE
OAK RIDGE NATIONAL LABORATORY
ORAL HISTORY PROJECT
INTERVIEWED BY
STEPHEN H. STOW
AND
MARILYN Z. MCLAUGHLIN (ASSISTANT)
OAK RIDGE, TENNESSEE
APRIL 30, 2003
TRANSCRIPT BY
BRIAN VARNER
2
STOW: Today, we’re going to be talking to three individuals -- Mike Wilkinson, Fred Young,
and Ralph Moon. They have all been very much involved with neutron scattering and materials
analysis work here at the Laboratory, starting as early in some cases, as 1950. So, we look
forward to a good talk with them and learning more about the history of neutron scattering in the
Solid State Division, High Temperature Materials Laboratory (HTML), Advanced Neutron
Source (ANS – never built), Spallation Neutron Source (SNS), and other important parts of Oak
Ridge National Laboratory and its history.
We’ve started off our interviews typically by asking how and why you got interested in science or
technology. Fred, give us a quick review of what got you into this area to begin with years ago.
YOUNG: It’s not an easy answer -- not a short one. I went to graduate school and only there did I
begin to realize what science was all about. And, I had a really interesting professor, who had a
big influence on my becoming a scientist and deciding to try to compete worldwide in research as
opposed to taking a teaching job at a small school or a job in industry, which were common
things to do at that time. And, it just happened at about that time that Oak Ridge National
Laboratory became open to the public. Oak Ridge Associated Universities, or ORAU, started a
program of having college and graduate students and faculty members come for the summer. I
asked ORAU if it would be possible for me to come to ORNL for a year. This was about the time
I graduated. And, they thought about it a little bit and decided it would be a good thing, so I did
that.
STOW: That was about 1950, right?
YOUNG: Yes, 1950.
STOW: Okay.
YOUNG: I spent a year here and then went back to the University of Virginia, which was part of
the agreement. I finally came back to the Lab in 1956 and stayed here until I retired.
STOW: Did you have any idea at that time that you'd spend your entire career here?
YOUNG: No, not really. But I had more connection with it than most people when they came
because I spent a year here and then I was a consultant in between. So, I was here frequently and I
pretty much knew what I was getting into when I came back. So I thought I would stay here a
long time, anyway.
STOW: Mike, what got you into science originally?
WILKINSON: Well, I guess I really got interested in science in high school ... taking courses in
chemistry and physics and mathematics. And, I really liked them very much. When I went off to
college, I actually thought I was going to be a chemist. But a very good professor I had in my
first-year physics course -- he was department chairman -- influenced me to change my mind and
become a physicist. After I graduated from the Citadel, I immediately went into the Army, which
sent me to radar school at Harvard and MIT. I spent most of my time in the Army as a radar
officer. At the end of the war, I decided to go back to MIT and pick up where I had left off in
radar school. I guess the professors I had there made me very interested in research. Prior to that,
I think I’d wanted to be a teacher. But, I decided I wanted to get some research experience first.
also wanted to come farther south. About the only place you could do research at that time and
3
come farther south, without being associated with a university, was Oak Ridge. And, my
background at that time fit in pretty well with ORNL’s Neutron Scattering Program.
STOW: Yes.
WILKINSON: At that time, there was no such thing as “training” in neutron scattering. I mean,
it was brand new and you just had to have a background that was somewhat similar, and I had
that. I came here and went to work with Ernie Wollan and Cliff Shull.
STOW: Yeah, we’re going to talk about them in just a minute. Now, Ralph, you’re the new kid
on the block here.
MOON: That’s right.
STOW: What got you interested in science?
MOON: Well, I think it started in high school. Math and science were my favorite subjects. My
father was an engineer, as was my older brother. I just assumed that I would be an engineer so I
enrolled in the engineering school of the University of Kansas. And, it was during my freshman
year as an engineer that I discovered (laughs) I really didn't want to be an engineer.
STOW: Yes.
MOON: I much preferred a little more freedom to do basic science, so I switched to pursuing a
bachelor of arts degree in physics. And, I haven't regretted it. Eventually, I ended up at MIT in
graduate school just when Cliff Shull, who had left Oak Ridge to go to MIT, was getting his
experimental program started at MIT. So, I was his first Ph.D. student. And, it was sort of natural
for me to come to Oak Ridge.
STOW: And, that was in ’63, I think.
MOON: That was in ’63. And, I just continued what I started under Cliff Shull at MIT.
STOW: Is it safe to say that neutron scattering really had its birth here at Oak Ridge -- with the
Graphite Reactor?
MOON: Oh, it did. No question about it.
WILKINSON: Oh, absolutely.
STOW: With Ernie Wollan and Cliff Shull.
WILKINSON: Yes, that's right.
STOW: In retrospect, what was the importance of the work that Wollan started before Shull
came?
WILKINSON: Actually, Cliff won the 1994 Nobel Prize in Physics for the [pioneering neutron
scattering research at the Graphite Reactor], but there's no doubt that it was a two-person
program. Many times Cliff stated that it was just too bad this award wasn't made many years
earlier when Wollan was still alive, so he could have been a co-recipient. But, Wollan did start
4
the program at the Graphite Reactor in November of 1945. He actually had sent here a
spectrometer that had an X-ray spectrometer that he used at the University of Chicago. He
installed it at the Graphite Reactor. Incidentally, this spectrometer is now on exhibit at the
American Museum of Science and Energy in Oak Ridge. But, at that particular time, the main
interest was in measuring the scattering power of atoms by neutrons. And, I won't go through all
of the details of what they went through, but the point is -- unlike X-ray scattering where you can
calculate the scattering power -- you can't calculate it for neutrons. You have to measure
everything experimentally.
STOW: Yes.
WILKINSON: And, before you could measure the first one -- you had to put the technique on an
absolute basis -- a quantitative basis. They went through many trials and tribulations. One of their
first successes was the use of powders, instead of single crystals, to scatter the neutrons. This
switch eliminated the problem of extinction that you have with large single crystals. I won't go
into that detail either, but it's a rather complicated effect that involves scattering within a large
crystal such that the scattered intensity [of the neutrons] is quite different from what you should
be getting. I think their use of polycrystalline materials was really the key to the success of their
whole program. After that, they had to untangle a lot of things, such as the isotopic effects of
scattering and the spin incoherent effects of scattering from a nucleus. They had a lot of problems
with multiple scattering. But, in any event, they were able to put this technique on a firm
foundation and use it for some very important experiments in nuclear physics, crystallography,
and magnetism. The crystallography work was primarily associated with hydrogen atom
crystallography. You cannot locate hydrogen atoms by X-rays because the X-ray scattering power
of hydrogen is very small. So, [hydrogen atom crystallography using neutrons] turned out to be
an entirely new field in itself. And, Henri Levy started a program within the Chemistry Division
here based strictly on hydrogen atom crystallography to measure the positions of hydrogen atoms
in crystals and study hydrogen bonding. Cliff and Ernie focused on magnetism, which is the other
very important field. But, the really important thing is that they did all this work here first. If they
had not established the foundation for [neutron scattering research using a reactor], it would not
have grown up around the world as it has.
STOW: For the laymen out there -- put in simple ... terms -- what's the practical importance of
neutron scattering? What does it tell us? I mean, what is the purpose of it?
WILKINSON: Well, the purpose of neutron scattering is that it is one of the best techniques
available for studying the properties of materials and characterizing materials. If you want new
materials in any technology you need, you've got to actually be able to study and characterize the
new materials properly. Neutron scattering is one of the best techniques you can use. It has made
a tremendous impact not only in physics and chemistry, but also in biology and various types of
engineering polymers and medical problems. It's just a tremendous technique.
STOW: And, Ralph ...
MOON: One interesting bit of history that Mike skipped over is that the first instrument Ernie
Wollan brought from the University of Chicago was actually designed by Arthur Compton, who
was a Nobel Prize winner and Ernie's thesis advisor. This instrument was used by Compton and
Wollan in Chicago and then Wollan brought it here. Some twenty or twenty-five years later, it
was in use again on another piece of Nobel Prize-winning research.
STOW: My goodness.
5
MOON: So, it's really a unique piece of apparatus. And, it still exists at the American Museum of
Science and Energy here in Oak Ridge.
STOW: I'll be darned. I didn't realize that. I ought to go over there and take a look at it.
MOON: Well, it's hard to find.
STOW: Is it?
MOON: I mean, it has been on conspicuous display occasionally, but not routinely.
STOW: Well, now, Fred, you were more into materials analysis, weren’t you? Tell us a little bit
about the work that you’ve done in materials analysis and radiation effects, and so on.
YOUNG: Yes. Well, the Solid State Division was actually formed to study radiation effects in
solids. Neutron scattering was not a part of the Solid State Division in the beginning. The Solid
State Division was formed in various steps in the late '40s. And, about 1951, it actually became a
division. In the beginning, there was no study of this sort going on at Oak Ridge National
Laboratory at all. But, it was realized early on that energetic particles striking solids would cause
disorder in the lattice of these solids. Most of the materials we have been interested in are
crystalline materials. A crystal is defined as an ordered arrangement of atoms.
STOW: Sure.
YOUNG: And, where the arrangement is disordered, a defect exists. If an atom is out of place,
that's a defect. Or, it could be a group of atoms out of place. There are various kinds of defects.
This was a subject itself that was just in its infancy at the same time that the study of radiation
effects was in its infancy. So, the two were used in complementary ways and "grew up together,"
so to speak. I was fortunate enough to be at the right place at the right time and participate in that.
And, so we investigated here in the division, all sorts of materials. It was important practically to
know what happened. We had to build reactors, and the materials the reactors were built of were
exposed to fast energetic particles, such as neutrons, alpha particles, protons, electrons, and
gamma rays.
STOW: Sure.
YOUNG: First, we had to put [target materials] into the Graphite Reactor and see what happened
to them. And, we had to develop methods of measurement to make quantitative statements about
a material. There was some theory, but not much. All of this developed sort of simultaneously,
and we were part of it. We looked at metals, semiconductors, ionic crystals, polymers, and
elemental materials like graphite, for example. It turned out that Doug Billington was one of the
early people here in [research on materials]. He actually came to the Oak Ridge School of
Reactor Technology first after the war was over. And, then he became head of the Solid State
Division. He did some of the first experiments and saw clearly that [studies of radiation effects on
materials] should be expanded. He led that program for twenty-five years approximately.
STOW: Of course, all three of you fellows had been the head of the Solid State Division either in
acting capacity or a longer-term capacity. Solid State Division is an interesting name.
MOON: Well, you know, it's been changed ...
6
STOW: It's been changed around, I know. [It became part of the Materials Science and
Technology Division at ORNL.]
YOUNG: The term solid-state physics became the name of a division of the American Physical
Society, in 1949, if I'm not mistaken.
STOW: Okay.
YOUNG: I think that's correct. And, it was called solid-state physics. But, there's also a field
called solid-state chemistry.
STOW: All right.
YOUNG: And then, there were the terms metallurgy, ceramics, and polymer science. All of these
fields dealt with solids. We had a group of people investigating various solids who were trained
in chemistry, physics, or ceramics sciences.
STOW: Yes.
YOUNG: And so, rather than call it any one of them, they started just calling it "Solid State."
That was a discussion that went on at the time that the division was first named.
WILKINSON: I think a better name probably would have been the Solid State Sciences
Division.
YOUNG: Yes, I think it would have. But, the managers did not name it that.
STOW: Well, I've always been curious about where the name came from. I mean, it could have
been the Liquid State or Gaseous State Division. (laughter) As I was reading about the
background of the division and some of your backgrounds, I learned there was a Research
Materials Information Center established in the 1960s in the division. Who can tell me something
about that?
WILKINSON: Well, I'm sure that Fred or I, or Ralph could, but let me just start.
STOW: Okay.
WILKINSON: As Fred said, most of the very early work in the division involved studying the
production of defects [in crystalline materials] and annealing these defects by raising the
temperature of the sample. Well, if you start off with a sample that already has a large number of
defects in it, then you actually end up "masking" the whole situation that you're studying.
STOW: All right.
WILKINSON: So it was pretty apparent at the time that very nice, perfect crystals that were
defect free and of high purity were needed in these research investigations. The Materials Science
Division of the Atomic Energy Commission at that time decided it would be nice to start a
program that would actually concentrate on developing techniques for producing very-highquality
materials and using the materials, not only in Oak Ridge, but also at other laboratories
sponsored by the Atomic Energy Commission.
YOUNG: And also worldwide.
7
WILKINSON: At roughly the same time, an information center was set up for keeping track of
where these materials were being prepared, who was preparing them, what their characteristics
were, how to go about getting them. And, an up-to-date list was published periodically and sent
both to the research users of the materials, and to the producers. The users needed to know where
they could get the materials, and sending the list to the producers kept them from duplicating
what was already being done someplace else. It turned out to be a small program. But, at the time,
we didn't have information centers all over the place like we have now. We didn't have a lot of
people concentrating on growing large single crystal specimens, so it was a very important
program.
STOW: What ever happened to that information center?
YOUNG: It lived its life.
WILKINSON: That's right. The other information centers in material sciences were developing
throughout the country under the sponsorship of other agencies. There was a big overlap in the
programs. The ORNL center was run by a research program, not by a DOE administrative
program. The Lab decided it was better to spend the money for research because the information
center duplicated the efforts of other organizations.
STOW: Okay. Let me ask about one other historical aspect. Fred, maybe you can reflect on this
best. In 1962, some pioneering work was done on ion channeling. Can you explain the
importance of that?
YOUNG: Yes. In general, atoms are aligned in the lattices of crystals. If you make a model of
this lattice, you can look through it in one direction. You can see many more holes all the way
through than if you look in a random direction.
STOW: Yes.
YOUNG: So, if you look in specific directions in a model of a crystal, your natural reaction is
that holes are in there. But, these models are not realistic either; in fact, the electrons orbiting
around the nuclei in all positions overlap and join in these open areas. So, we had begun to think
that in a cubic lattice [the movement of atoms through a crystal] was isotropic. For instance,
atoms diffusing through the crystal would diffuse in all directions with equal ease, with equal
velocity. We had convinced ourselves in a way that holes did not really exist throughout the
lattice. But then, in order to explain some scattering results, Mark Robinson became involved in
an experimental program. He started doing some calculations in a time when general use of
computers was just beginning. He was rather clever at using computing in ways that were
somewhat more advanced than what other people had been able to do. He found experimentally
and theoretically that when atoms were sent down in a certain direction in a crystal, they
penetrated a lot farther in that direction than in other directions. What’s more, the atoms moving
in that direction were not just the ones sent directly along the lattice, but also the ones that
bounced off atoms in the crystal in a way that let them go through it farther. This phenomenon,
discovered at ORNL, is called channeling.
STOW: All right.
8
YOUNG: They decided to name it ion channeling because the lattice "channeled" charged atoms,
enabling the projectiles to go through the crystal. And so, at first, we wondered whether this was
true or not, you understand. And then, lo and behold, some people at Chalk River Laboratory in
Canada who were investigating ion implantation discovered the same effect, which was found to
be channeling. And then, the whole world woke up to the new phenomenon, and immediately it
began to be a very important subject. Robinson continued his research with Ordean Oen, and
Mark and Dean together performed the calculations. They broadened their program and then we
began to develop programs here. And, at the present time, ion implantation is used to adjust the
concentration of charged carriers in semiconductors.
STOW: Yes.
YOUNG: And, this understanding of channeling is the basis of that whole industry now.
Channeling effects must be taken into account properly. You can't do ion implantation exactly
along the axis of a silicon crystal. You've got to cock it off just a little bit.
STOW: Yes.
YOUNG: And then, you can determine exactly how far all the atoms will be implanted into it.
And, I mean, this was a tremendous achievement. We're in the silicon age, aren't we? This is of
tremendous importance to the whole industry. It turned out also that some really nice theoretical
and experimental studies were done here, showing you could use this as a way of determining
interatomic potentials.
STOW: Okay. So, a lot of that fundamental work that we're benefiting from today in silicon
technology came out of the Solid State Division in those years.
YOUNG: That's quite true.
STOW: Neutron scattering -- the Neutron Scattering Program -- has really been one of the
longest continuing programs at ORNL stretching back to 1945. How has the program changed as
new reactors have come online? We started with the Graphite Reactor, and, of course, have been
through thirteen, fourteen, fifteen different reactors here at the Laboratory over the years. How
have changes in reactor technology influenced the neutron scattering program and its ability to
achieve new objectives? Ralph, would you want to jump in on that?
MOON: Yes, sure. Three reactors have played key roles in the Neutron Scattering Program. The
first was the Graphite Reactor, where the flux of neutrons is measured in neutrons per square
centimeter per second. That number tells you how many neutrons are flowing into your
experiment. At the Graphite Reactor, that number was around 1012 neutrons per square centimeter
per second. We then went to the ORR, the Oak Ridge Research Reactor, where flux number
increased enormously to 3 times 1014 -- a factor of 300 larger than the flux at the Graphite
Reactor. Finally, we did neutron scattering research at the High Flux Isotope Reactor, where the
neutron flux was boosted to 1015. What happened is that the complexity of the experiments
followed that increase in flux. When you get more flux, you usually don't just do experiments
faster. You do experiments that you couldn't do before because you didn't have enough neutrons.
So, at the Graphite Reactor, elastic coherent scattering was the main technique used because the
researchers could measure the number of neutrons scattered through a particular angle. Beginning
at the ORR, another type of experiment involving inelastic scattering, in which both the number
of neutrons scattered through a particular angle and their change in energy could be measured.
9
So, neutron cross sections were measured as a function of energy and momentum. When we got
to the High Flux Isotope Reactor, we created a new sort of experiment, in which we not only
measured the scattering angle and energy change, but also the spin of the neutrons in a beam. In a
magnetic field, the spin of one half of the neutrons can be either up or down. We'd known for a
long time how to produce polarized beams of neutrons, so we could produce a beam where the
spins of all the neutrons are up. We also had the technology for flipping those spins from up to
down. So, what we did at the HFIR was -- in addition to measuring energy and momentum
changes – was to measure how many neutrons in a beam came on the sample up-spin and how
many came off the sample up-spin.
STOW: Okay.
MOON: A different problem was to determine how many neutrons came on the sample with
down-spin and how many came off the sample with a down-spin. Also, we tried to determine the
probability that some neutrons would flip their spin – come into the sample up-spin and come off
the sample down-spin. Theory told us that for certain types of systems, all those cross sections
(probabilities) would be different. We found new information in each "spin dependent" cross
section. We experienced a gradual evolution as experiments became more and more complex as
the source flux got bigger.
STOW: So, we've had three reactors that have influenced the program -- the Graphite Reactor,
the Oak Ridge Research Reactor, and the HFIR.
MOON: That's right.
STOW: But, Mike, there are sources of neutrons that are not from reactors, right?
WILKINSON: That's right.
STOW: Has the Neutron Scattering Program here relied solely on neutrons from nuclear
reactors?
WILKINSON: Well, are you thinking in terms of accelerator-type neutrons?
STOW: Yes, I think so.
WILKINSON: Well, there's been very little neutron scattering here done using accelerators.
Herb Mook has done some experiments at our accelerator facilities, but, of course, a lot of it is
going to be done fairly soon on an accelerator when the Spallation Neutron Source is finished.
STOW: That's right.
WILKINSON: The types of experiments you do at research reactors and accelerator-based
neutron sources, such as the SNS, are a little bit different, but, nevertheless, equally as important
and equally meaningful, with respect to the information you get. In the pre-reactor days, scientists
observed neutron scattering using very small sources, such as radium-beryllium sources, but they
didn’t learn anything, because there were not high enough intensities to do any meaningful
experiments.
STOW: Fred, you were involved in the 1970s with the planning and the establishment of the
High Temperature Materials Laboratory. Tell us a little bit about your involvement there.
10
YOUNG: My involvement really started at the time when the Atomic Energy Commission
became the Energy Research and Development Administration and then the Department of
Energy. At that time, we were constrained to study materials of interest to the nuclear programs.
We weren't funded to look at anything we wanted to.
STOW: Yes.
YOUNG: With the onset of the Department of Energy in 1977, we were asked to investigate
materials problems related to all energy technologies. So, this opened up a tremendous new area
for us. It became apparent immediately that for many of the energy technologies, including
nuclear, high-temperature materials were very important [because fuel is used more efficiently
when machines are operated at higher temperatures, but research is needed to identify or create
structural materials for such machines that can endure high temperatures for a long time]. We had
no programs in that area to amount to anything in the whole country in the atomic energy
laboratories. So, the origin of the HTML here began when Don Stevens, head of this program,
asked me to meet him in Washington. Then he asked me to go to several other laboratories
around the country and determine what was going on in the area of high-temperature materials,
and what we should be doing about that. Well, after a long process, I came back and wrote a
report in which I stated that some really exciting [research on high-temperature materials] could
be done here. I said that it was appropriate for the Department of Energy to sponsor a program of
this sort. Well, it took many years to realize [this vision], but ultimately, the High Temperature
Materials Laboratory [was designed and built at ORNL]. And, I was involved with it over that
whole period of time. It was finally decided to put HTML into the Metals and Ceramics Division,
as opposed to the Solid State Division. That was a somewhat arbitrary decision but not an
unreasonable one. And, I was proud of my efforts in that respect. I think I had a lot to do with it.
STOW: Well, that's something to be proud of, because the HTML is one of the cornerstones of
our materials science work here in Oak Ridge.
YOUNG: Yes, yes. It was created out of whole cloth in a way, because there was almost no
[study of high-temperatures materials] here. And, almost none in the whole set of DOE
laboratories.
STOW: Well, Fred, you've touched on a couple of things that I want to ask you about, Mike. You
were division director for Solid State Division starting in 1972, I believe, and up into the 1980s.
So, you were division director during the transition from the Atomic Energy Commission to
ERDA to DOE. As manager of the division, did you experience problems with that transition?
WILKINSON: Well, we didn’t experience any problems. It sort of opened the door for us. The
point is that the research done in the Solid State Division is mission-oriented research. That
means that you do research on materials and their properties that are important to the mission of
your sponsor. There's one exception to that I might point out, and that's the Neutron Scattering
Program. The exception is that, it's acceptable to use the major facilities that have been built by
the sponsor here at the Laboratory to study materials of any kind that can't be studied by other
techniques.
STOW: All right.
WILKINSON: For the Lab’s Neutron Scattering Program in the Solid State Division, the
determination of which types of materials to study was not as restrictive as was the case in other
parts of the division. But, under the Atomic Energy Commission, of course, we were restricted to
11
work on materials associated with fission and fusion reactors. Under ERDA and then the
Department of Energy, materials associated with all energy technologies were of interest. ERDA
and DOE’s mission [embraced] not only fission and fusion energy, but also fossil energy,
geothermal energy, magnetohydrodynamic energy, energy storage, energy conservation, and so
forth. Well, all of these [energy technologies] were materials limited. Advances in energy
technologies [to increase supply and reduce demand] required new materials. So, it was very
interesting from my viewpoint to be [encouraged] to expand our program from a fairly restricted
one involving mostly materials radiation and neutron scattering, to almost anything else we
wanted to do. And, we got some extra money for starting new programs, but a lot of it was
associated with redirecting some of the programs in radiation effects to other areas. As a matter of
fact, nowadays relatively little research is going on in the radiation effects studies; most of this
type research is tied into other efforts in a very broad program. It was a tremendous opportunity
for us to be able to expand our investigations. The Solid State Division has developed into one of
the broadest materials programs in the world, and certainly one of the best. It's one of the best
organizations in the world for studying different types of problems in the materials sciences.
[Since 2009 SSD and the Metals & Ceramics Division became parts of the newly named
Materials Science and Technology Division at ORNL.]
STOW: Well, in 1971, I think, Alvin Weinberg, Laboratory director, asked you and Sheldon
Datz to look into opportunities in nonnuclear research and the basic physical sciences. Is what
you've just described an outcome of some of Alvin's foresight?
WILKINSON: Alvin jumped the gun here in that he established committees for looking into
[areas of nonnuclear energy research]. We did actually publish a report on it, which the
Department of Energy found very useful, once they got involved in all other types of energy. As a
matter of fact, the so-called nonnuclear energy technologies and the materials associated with
them turned out to be key to their programs.
MOON: You mentioned Alvin’s forward-looking thinking. Let me mention one example of that.
STOW: Okay.
MOON: From the beginning, he had recognized that neutron scattering was very important
scientifically, but he played a really crucial role when the HFIR was being built. The HFIR was
designed to produce transuranic isotopes but the original design had no provision for neutron
scattering.
WILKINSON: No beam holes ...
MOON: No beam holes. Alvin Weinberg insisted that they could not build this reactor without
putting in beam holes [for neutron beams] so that neutron scattering could be done at the reactor.
STOW: And, they put in four beam holes, I think.
MOON: Four beam holes, yes.
STOW: So, that really was a key part of the Neutron Scattering Program.
MOON: Absolutely, yes.
12
WILKINSON: Well, the engineers were afraid, because of the type of reactor it is. They said
they were afraid that putting in the beam holes would affect the operation of the reactor. That's
the reason they compromised on just four beam holes. It's too bad they didn't put in a lot more.
But, as it turned out, of course, the beam holes did not affect the operation of the reactor and have
really been a tremendous help to the Neutron Scattering Program here at the Laboratory.
STOW: Fred, you took over as division director in 1988, I believe. What were your feelings and
thoughts at that point in your career in taking over an administrative role like that?
YOUNG: Well, unfortunately, my time as division director was simultaneous with [the visits of
and issues raised by] the so-called Tiger Teams. [They were sent to ORNL by DOE to check on
compliance with environmental, safety, and health regulations].
STOW: Okay.
YOUNG: (laughs) So, a lot of my efforts had to go toward dealing with those issues. I didn’t
enjoy that very much. Doing research is much more fun than being an administrator. But, I think
Mike told me this one time: it didn't make so much difference about how many more research
papers I published, as it did whether the Solid State Division developed into a powerful
institution as it did.
WILKINSON: Well, let me interrupt him for a minute.
STOW: Okay.
WILKINSON: He didn't just become a division director and become involved in the
management of the division. Fred had been an associate director for a long time ...
STOW: Sure.
WILKINSON: ... and as associate director, he had also been highly involved in division
management.
YOUNG: You know, I was quite familiar with management, and so it wasn't an exceptional
chore ...
STOW: I understand.
YOUNG: ... except for this Tiger Team business. That was pretty late in my life here.
Unfortunately, it was a time of change in the Department of Energy and its way of funding things.
Funds were taken away from research programs to help solve the cleanup problems that we had
from earlier handling of radioactive materials here at Oak Ridge.
STOW: Yes.
YOUNG: And, I felt that was unfair. We had not been the ones that had caused the problem, but
we had to pay for it. And, we did get a chunk of that. But, nevertheless, it was also an exciting
time because we were doing a lot of new and interesting research then. I was proud to be part of
it. I did want to make an addition to what was said earlier by Mike and myself on the studies of
irradiation effects.
13
STOW: Okay.
YOUNG: By the end of the 1970s and early ‘80s, we had, to a large extent, both theoretically and
experimentally, categorized the irradiation effects. And, they were reasonably well understood
then.
STOW: Yes.
YOUNG: And, so it was natural that we use this expertise to investigate other types of problems.
We went from being certainly one of the best-- if not the best -- radiation effects laboratories in
the world -- to one of the best general solid-state physics laboratories in the world, over a few
years, from the onset of DOE to the time I left. We opened up a lot of new areas of research that
utilizes the facilities and people that we had. And, that's what research management is about, and
that part is okay. It's just those Tiger Teams ... (laughter)
STOW: I get the impression you didn't care for the Tiger Teams that much. I don't think anybody
did, frankly. (laughter) Ralph, you served as an acting director of the division for a period of
time, but I want to ask you more specifically how you got involved with the ANS. Tell us a little
bit about your involvement there and what happened to ANS in the long run.
MOON: Well, there's a lot of prehistory to the ANS, which is also prehistory to the SNS ...
STOW: Yes.
MOON: It started when both the High Flux Isotope Reactor here, and the High Flux Beam
Reactor at Brookhaven National Laboratory, were built and came online in the mid-1960s.
Shortly after that, the neutron community, not only the scattering community, but other scientists
that used reactors, got worried that DOE -- or I should say at that time, the AEC – was not
thinking ahead about the next-generation neutron source.
STOW: Yes.
MOON: There was a workshop in '73 called “The Workshop for Intense Neutron Sources,” held
at Brookhaven. From this Lab, Mike, Alvin Weinberg, and Wally Koehler went to it. Their
recommendation was that the AEC should really start thinking about the next-generation neutron
source. At that time, Argonne National Laboratory had already started thinking about “pulsed
sources,” or spallation sources of neutrons.
STOW: Okay.
MOON: ... so that was in 1973. And in ‘77, a National Research Council group did a study of
neutron sources, with Cliff Shull as the chairman. The group recommended that people in charge
should start thinking about new neutron sources. In 1980, a DOE panel headed by Bill Brinkman
made the same recommendation: start thinking about new neutron sources. In '83, there was a
local competition. Alex Zucker and Herman Postma had decided that it was time for the
Laboratory to go after a big new facility and that it was going to be a neutron source.
STOW: Okay.
MOON: So, the next decision to be made was whether to go for a reactor or for an acceleratorbased
spallation source. And, I was the guy in charge of making arguments for the reactor. Dave
14
Olsen was in charge of making arguments for the spallation source. So, we had a big management
meeting in which we both presented cases, and the Laboratory decided to go for a new reactor.
Well, the decision was made at that time to upgrade the HFIR. Postma and Zucker didn't want to
go for a new reactor. They wanted to upgrade the HFIR. We got money starting in '84 from the
internal Laboratory Directed Research and Development (LDRD) Program to begin a small
project about planning upgrades to the HFIR. The same day we got that money, we received an
invitation to appear before another National Research Council meeting in March. It was January
1984 that we got the money, and we had to appear in March before the National Research
Council group, whose mission was to decide which major facilities DOE would fund. This was
the Seitz-Eastman committee. They decided that DOE’s first priority should be to build an X-ray
synchrotron source, which became the Advanced Photon Source, the APS [which was built at
Argonne National Laboratory]. The Advanced Neutron Source (ANS) reactor was the second
choice. Argonne representatives were there touting an [accelerator-based] spallation source,
which was the fourth choice. At that point, the decision was made to go for a new reactor. This
committee didn't want an upgraded HFIR. They wanted a brand new facility. So, the ANS took
off from that point. When it came to funding the ANS, the federal government found it was a lot
more expensive than people thought, and the timing was wrong. Our country was having these
massive deficits every year. So the decision was made to not fund the construction of the ANS,
but the scientific case for a new neutron source had been made.
STOW: Yes.
MOON: And, the decision had been made to put a neutron source in Oak Ridge. So, the decision
to try for a spallation source was natural, and the timing was right. When the conceptual design
report was completed and DOE wanted to ask for construction money, we had this magic moment
when there was a surplus in the federal budget. And, that was very important, I think, in getting
funding for the spallation source. But, the whole prehistory -- the scientific case for a new neutron
source was made beginning in 1973 and going up to now -- and when the arguments came about
whether a spallation neutron source should be built in Oak Ridge -- the scientific case had already
been made.
STOW: That's an interesting history. I didn't realize all that. And, we'll be talking to Al
Trivelpiece about his role in the SNS. So, I appreciate the background there. Mike, let me ask you
one quick question here.
WILKINSON: Could I insert something? I've just been sitting here thinking about our
conversations involving, particularly, the neutron scattering and materials research, and in all of
this, Wally Koehler's name has not been mentioned.
MOON: I was going to mention him ...
WILKINSON: I wanted to make sure that we recognize that Shull and Wollan started the
program, and Wally Koehler joined their group in 1949 ...
STOW: Yes.
WILKINSON: ... I became the fourth member in 1950, and Wally stayed here and performed
some beautiful neutron-scattering research for many years. As a matter of fact, he led the classic
work done here on interpreting the magnetic scattering from rare-earth metals and alloys, and
both he and the Laboratory got a lot of credit for it. I just want to make sure that this oral history
mentions his name.
15
STOW: Good. I'm glad you did. And, let me follow up on that. I'm going to ask all three of you
the same question. In your career here at ORNL, has there been any particular individual who has
influenced you in a positive fashion, been your mentor, or influenced the direction in which your
research has gone? Mike, do you want to answer that?
WILKINSON: Well, there’s no question in my mind that Cliff Shull was a very strong influence
on what I did here. When Ralph said he was Cliff’s first graduate student, I wanted to say, “Well,
I was Cliff’s first postdoctoral student.” I really didn’t come here in a postdoctoral position, but a
postdoc is what I was. I worked with him very closely for five years and learned a tremendous
amount from him. So, there’s no question that as far as my research was concerned, he was the
main influence.
STOW: Ralph, what about you?
MOON: Yeah. Well, certainly Cliff influenced me when I was a graduate student, but when I
came here, I started working closely with Wally Koehler ...
STOW: Yes.
MOON: And, we collaborated closely for probably, sixteen, seventeen years after I came here in
'63. I certainly learned a lot from Wally and benefited from his experience and his choice of
scientific experiments to go after.
STOW: Fred, do you have any insights on this?
YOUNG: Well, I didn't have the same type of experience. There was not a world-famous
scientist in my area that I learned from. I was on my own more from the very beginning. But, one
thing that helped the Solid State Division, in my view, was the interaction we had with other
laboratories and universities in this country and around the world. And, in particular, I would like
to mention a theorist in solid-state physics named Gunter Liebfried, a German located at the
University of Aachen. He had learned his solid-state physics as the field grew up in Germany
prior to World War II when it was put on a firm theoretical quantum-mechanical basis.
STOW: Yes.
YOUNG: He spent one year here and then, after that, a couple times [during each of the next few
years] he would come to ORNL and stay six weeks and work with theorists primarily. But he also
worked with me a lot.
STOW: Okay.
YOUNG: And, I learned an awful lot from him. I got just a basic sort of understanding of solidstate
physics, because I was not trained in that area at all, you understand. And, he had a big
influence on me. Other than that, everybody influenced me. I was getting all the help I could at all
times, but I didn't have a mentor in that sense.
STOW: All right. Fred, look back on your career and tell me if you have one research
accomplishment that you’re most proud of. I want to ask all three of you to quickly reflect on
that.
YOUNG: I developed techniques for looking at defects in metals that scientists have used since.
16
STOW: Good.
YOUNG: I think that was the way I became recognized scientifically in this country and around
the world. I was able to prepare samples of copper and then do experiments with them to show
that I knew what I was talking about. This was new entirely for metals, in particular, at that time.
And, I gained some national and international recognition for this work.
STOW: Mike, what would you be most proud of as a contribution to science?
WILKINSON: Well, actually, as far as research is concerned, the work that I did with Cliff Shull
was, I think, extremely important. But, I continued studies of magnetic materials after he left, and
I think I did some very important work there. But, I would like to think that I would be
remembered as much as anything else for the developments that took place in the Solid State
Division. Fred and I worked very hard on this and it became one of the best organizations in the
world for doing research in materials sciences.
STOW: Good.
WILKINSON: I think that both of us would like to be remembered as much as anything else for
our contributions in making it happen.
STOW: Well, we'll make sure you are. (laughter)
YOUNG: I think that we both realized at sometime relatively early on that that was a role that we
were best suited for, given the circumstances here and the people here. We gave up our treasured
experiences as experimental scientists in order to help everybody else do a better job.
STOW: Well, it takes all sorts of people to make this place operate. And we’ve interviewed some
people who acknowledge that. They have said something like “Hey, I was not a good scientist
necessarily, but I was a better administrator.” And Ralph, what would you say your greatest
contribution has been?
MOON: Well, it was one of the early experiments at the HFIR, where we developed the
polarization analysis technique. It came about in almost an accidental way. A fellow named
Tormod Riste, who was an outstanding scientist from Norway, came to Oak Ridge. I was going to
work with him on doing some other experiment at the HFIR, one of the first experiments to be
done out there. We actually started that experiment when the HFIR went down because of a
problem, and [the shutdown] lasted six weeks. Tormod was sharing an office with me, so we
often talked about neutron scattering and the theory of neutron scattering. It came to us that we
already had the equipment to do some very interesting experiments related to measuring whether
the neutron had flipped its spin [from up to down, or vice versa] or not when it scattered from a
sample. So, we just forgot our plans to do this original experiment and started thinking about
polarization analysis experiments. When Wally Koehler heard our conversations, he wanted to
become a part of that. So, that was it. The three of us did this kind of experiment. Everyday, it
was a different thing. We were trying something brand new that nobody had ever done before.
And, we had lots of opportunities for brand new experiments. It was just really great fun.
STOW: Good. Where would you guys say the center for neutron scattering is now worldwide? Is
it in Europe?
17
MOON: Yes. Probably at the reactor at the Institut Laue-Langevin in Grenoble, France.
WILKINSON: That has been for many years probably the world’s single largest center for
neutron-scattering research. The ILL reactor was built strictly for doing neutron scattering
research. It is a high-flux reactor with many beam holes. I think that the world’s center for
neutron scattering research is going to be taken away from ILL when the Spallation Neutron
Source (SNS) is operating and the modifications of HFIR are made.
STOW: Well, that's a good way to leave the interview then -- looking toward the future when
Oak Ridge will return as the world’s center of neutron scattering. Thanks very much, fellows.
MOON: Thank you.
WILKINSON: Thank you.
-----------------------------------------------END OF INTERVIEW-----------------------------------------